1. Field of the Invention
The present invention relates to an ultrasonic jointing method.
2. Description of the Related Art
An ultrasonic jointing method for jointing an electric wire with a terminal is known in which a conductor part of the electric wire and the terminal are held between a horn and an anvil, and the oxidation film and stains on the surface of the conductor part of the electric wire are removed by being applied ultrasonic vibration.
It is known that in the above ultrasonic jointing method, in order to prevent the jointing strength from decreasing due to the decrease of the cross-sectional area of the conductor part in the jointing region of the conductor part and the terminal, the ultrasonic jointing can be performed after pressing on the conductor part beforehand (referring to JP-A-2006-172927). Besides, it is known that in the above ultrasonic jointing method, in order to prevent that the pressing force of the central part of the horn becomes large and the pressing force of both side parts becomes small when the ultrasonic jointing is being performed, the pressing forces can be equalized by providing protrusions at the both side parts of the horn (referring to JP-A-2005-319497).